Disc drives are common data storage devices. A typical disc drive includes a rigid housing or deck that encloses a variety of disc drive components. The components include one or more discs having data surfaces coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor that causes the discs to spin and the data surfaces of the discs to pass under respective hydrodynamic or aerodynamic bearing disc head sliders. The sliders carry transducers, which write information to and read information from the data surfaces of the discs.
As the disc rotates, the disc drags air in a direction approximately parallel to the tangential velocity of the disc. With increasing disc capacity and evolving disc drive performance requirements, it has become desirable to increase the rotational speed of the discs in the disc drive. During disc drive operation, increases in disc rotational speed can cause windage-related excitation of the discs and other mechanical parts located within the disc drive housing.
One way to reduce windage-related interference is to include a shroud around the disc pack to substantially confine airborne filtering to the disc pack area. With higher disc capacity and performance requirements, most hard disc drives include a disc shroud feature around the disc pack to streamline the air flow and reduce the resonance from disc modes. At the same time, a lot of modern drives have an air borne filtering mechanism using a filter residing inside the disc drive in the middle of the main air flow path. In this kind of design, the main stream air flow around the disc shroud is divided into two branches, one routing to the filter area and the other around the disc, and then merging back again shortly as one branch in the disc shroud area. The design helps the particle clean up rate, but breaks the intact disc round shroud. As a result, more turbulence is introduced causing higher resonance from disc mode and bulk windage. It is known in the art that the non-repeatable runout (NRRO) will be improved if the shroud openings for the air filtering is blocked. However, with the filter area of the shroud blocked, the air borne clean up rate will be significantly worse.
Known disc drive designs allow, and in some instances encourage, the flow of air out of the disc pack area. This flow of air that escapes the disc pack area is typically able to indiscriminately re-enter the disc pack area, thereby causing the disc pack to experience windage-induced turbulence on a random basis. This windage-induced turbulence can have a negative impact on disc pack performance during critical read-write operations.
Various shrouds and baffles have been proposed to control air flow in a disc drive. For example, shrouds or baffles are used to control air movement at the edge of the disc to prevent disc flutter and to aid in filtering the air. In addition, filters supported in airways along the edge of disc housings are known in the art.
Embodiments of the present invention address these and other problems, and offer other advantages over the prior art.